An evaluation of the safety, side effects, how a drug enters and leaves the blood and tissues over time, and the biological activity of various doses of VX-497, a product designed to interfere with the growth of the virus hepatitis C. Hepatitis C virus (HCV) is an RNA virus of the Flaviviridae family. Acute infection with HCV causes a generally mild, often asymptomatic, acute hepatitis. However, at least 85% of patients infected with HCV do not fully clear the virus and develop chronic infection of the liver. Once chronic HCV is established, spontaneous clearing of the virus is rare and the majority of patients with chronic HCV develop slowly progressive liver disease. Twenty years after infection, most patients have evidence of ongoing chronic hepatitis and at least 20% have cirrhosis (scarring). Long-term problems caused by chronic HCV are cirrhosis, liver failure, and liver cancer. There is an estimated 8-10,000 death per year in the United States and is expected to increase over the next ten years. Until recently, the only approved treatments for chronic HCV have been recombinant interferon alfa and consensus interferon (Intron-A and Infergen/interferon alfacon-1). VX-497 is a potent enzyme inhibitor and antiviral agent. This study is a double blind, placebo controlled, three-dose trial, each dose group consisting of eight active and two placebo patients. Treatment will consist of three different doses of study medication. Patients will have the first dose for two weeks, the second dose for two weeks, and the third dose for four weeks. If two or more patients in any of the dose groups experience drug-related adverse side effects requiring termination from the study, escalation to the next dose group will not occur. All patients will be followed for four weeks after the treatment. Based on the results of the core study, patients will be offered the option to continue on the medication for three more months, after a four week period off the drug.